Railway track infrastructure wears and degrades continually from increasing traffic, heavy axle loads and increasing speeds. As rail, crossing and switch point surfaces wear, the railroads continually need to repair or replace the damaged surfaces. This has become increasingly more difficult with less available track time due to increasing traffic and train speed demands. Moreover, the need to repair this infrastructure becomes increasingly necessary due to regulatory requirements.
Manganese frog and diamond transition points are more susceptible to damage due to the wheel impact across the open transition points. Current repair processes utilize arc gouging and grinding techniques in the field to remove the damaged surfaces, followed by metal inert gas (“MIG”) welding of stick or wire manganese to layer, or build-up, new layers until more than the original dimensions have been achieved. The surface is then ground back down to the specified dimensions. The life of the repair is dependent on operator skill and ability to keep the temperature of the parent material under a specified temperature, 500 degrees F. The life of the repair also depends on the ability of the operator to remove slag between layers created by the MIG welding process. All of this is complicated by the environmental conditions and the time pressure to clear the track or switch for traffic needs.
It is often that rail surfaces having deep damage may be replaced completely instead of repaired. Rail surfaces are typically removed by replacing sections of the rail and welding in a new section with two Thermite or flash butt welds. This typically requires removing and replacing large sections of track.
To prepare a worn surface for repair, a section thereof of the worn surface is typically arc gouged and the heat affected zone is then ground smooth using a grinder and torch to remove arc gouging slag. An operator must typically utilize the grinder and torch by hand. Thus, it may be difficult for an operator to precisely grind away the surface fully to prepare for repair. In addition, because an operator typically utilizes the grinder by hand, the precise contours of the ground surface may be difficult to control. Moreover, grinding railway structures may be hazardous due to the propensity of the arc gouging, grinding and torch tools to throw sparks, which may cause fires, damage or injury, and the generation of fumes, which may be hazardous to operators' health.
Typical MIG welding of rail surfaces requires deposition of metal material, such as steel manganese alloys, at precisely controlled interpass temperatures. During the welding process, the temperature of the metal surface must typically be maintained at or below the specific interpass temperature, such as below 500 degrees F.
MIG welding often leads to voids, entrapped slag or metal oxide by-products, cracks and overheating between layers of deposited material, which can significantly reduce the life of a railway structure. The primary culprit in premature degradation of the manganese material is overheating. An operator must typically constantly stop or use forced air cooling to ensure the interpass temperature between layers is maintained below 500 degrees F.
In addition, typical welding creates slag materials or metal oxide by-products that must be scraped from the railway structure as metal is deposited thereon. Thus, after a layer of material is welded thereon, the slag is typically manually removed using all or a combination of descalers, hammering and wire brushing, and another layer is added thereto. Invariably, due to the chaotic nature of the weld process and human errors or lack of attention, weld slag is typically entrapped below and in the weld repair surface. Repairing worn or damaged surfaces of railway surfaces is often slow, tedious, inefficient and operator dependent.
A need, therefore, exists for a process for repairing railway structures. Specifically, a need exists for a process for repairing railway structures, such as rails and transition points, such as frog and diamond transitions. More specifically, a need exists for a process for repairing railway structures, such as rails and transition points, having surfaces worn and damaged by rail traffic.
Moreover, a need exists for a process for removing worn and damaged surfaces of a railway structure using a laser removal system. In addition, a need exists for a laser removal system that quickly, efficiently, precisely and cost-effectively removes metal surface material from worn and damaged railway structures.
Further, a need exists for a process to build-up surfaces of railway structures for repairing the same using a laser cladding, laser overlaying, or laser additive manufacturing system and process. Still further, a need exists for a laser cladding, laser overlaying, or laser additive manufacturing system and process that quickly, efficiently, and precisely deposits metal surface material to a railway structure to repair the same.
Specifically, a need exists for a laser cladding, laser overlaying or laser additive manufacturing system and process having large deposition rates using both powder feed and hot wire.
In addition, a need exists for a laser removal and/or laser cladding process for worn railway structures that is precisely controlled, and controls and reduces the amount of heat input into the railway structure. More specifically, a need exists for a laser removal and/or laser cladding process that maintains the temperature below 500 degrees F.
Further, a need exists for a laser cladding, laser overlaying or laser additive manufacturing system and process that utilize a variety of materials, such as powder, wire, strip and other like materials. Still further, a need exists for a laser cladding, laser overlaying or laser additive manufacturing system and process that can be utilized to building up a variety of 3D shapes, providing more control of the final shape of the repair and reducing or eliminating subsequent machining and grinding steps.
Moreover, a need exists for a laser removal and/or laser cladding process that is robotically-controlled. Specifically, a need exists for a laser removal and/or laser cladding, laser overlaying or laser additive manufacturing system and process that is automatically controlled, achieves high levels of gouging and/or welding, and provides high quality laser removal and/or laser weld overlays.